Planned Divestiture Of Northwest Operations (Schedule Of Assets And Liabilities Held For Sale) (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Planned Divestiture Of Northwest Operations [Abstract]
Accounts receivable, less allowances of $12	$ 49
Prepaid expenses	1
Contract acquisition costs	8
Other current assets	2
Property, plant and equipment, net	1,075	$ 1,049
Goodwill	658
Other intangibles, net	30
Other assets	17
Valuation allowance on assets held for sale	(434)
Total assets held for sale	1,406	1,401
Accounts payable	13
Advanced billings	18
Accrued other taxes	9
Other current liabilities	14
Pension and other postretirement benefits	29
Total liabilities held for sale	115	$ 123
Other liabilities	32
Allowance for accounts receivable, classified as held for sale	12
Pension liability	163
Pension asset to transfer	$ 98
Percent of pension liability to transfer	60.00%